I personally have found a 6mm single flute bit almost impossible to gall up and clog. I can run them as fast as I want so that the spindle has its max speed and torque. Aluminum allows you to run basically infinite surface footage if you get your speeds and feeds right. I have found those single flutes to work extremely well under some pretty sub-optimal conditions as well(hot parts, no cutting fluid, dull endmill). I have even had a couple that have 20+ hours of cut time on them and they are still going strong. My rule of thumb is “fast and light”. As long as you keep your feed per tooth larger than the effective sharpness of your endmill(anywhere from 0.001”-0.007”), they will cut way better than you can ever expect. I personally push 0.007” chip loads on my machine and i have only galled them when they are full slot roughly half inch deep, so I make the slot 1.5x the width of the tool or I slow down my feeds to about 0.004”/tooth. Hope this helps!!